English   español  
Please use this identifier to cite or link to this item: http://hdl.handle.net/10261/121272
Share/Impact:
Statistics
logo share SHARE logo core CORE   Add this article to your Mendeley library MendeleyBASE

Visualizar otros formatos: MARC | Dublin Core | RDF | ORE | MODS | METS | DIDL
Exportar a otros formatos:
Title

Bicarbonate is an essential constituent of the water-oxidizing complex of photosystem II

AuthorsAllakhverdiev, Suleyman I.; Yruela Guerrero, Inmaculada ; Picorel Castaño, Rafael ; Klimov, Vyacheslav V.
Issue Date1997
PublisherNational Academy of Sciences (U.S.)
CitationProceedings of the National Academy of Sciences of the United States of America 94: 5050-5054 (1997)
AbstractIt is shown that restoration of photoinduced electron flow and O2 evolution with Mn2+ in Mn-depleted photosystem II (PSII) membrane fragments isolated from spinach chloroplasts is considerably increased with bicarbonate in the region pH 5.0-8.0 in bicarbonate-depleted medium. In buffered solutions equilibrated with the atmosphere (nondepleted of bicarbonate), the bicarbonate effect is observed only at pH lower than the pK of H2CO3 dissociation (6.4), which indicates that HCO3/- is the essential species for the restoration effect. The addition of just 2 Mn2+ atoms per one PSII reaction center is enough for the maximal reactivation when bicarbonate is present in the medium. Analysis of bicarbonate concentration dependence of the restoration effect reveals two binding sites for bicarbonate with apparent dissociation constant (K(d)) of ≃2.5 μM and 20-34 μM when 2,6- dichloro-p-benzoquinone is used as electron acceptor, while in the presence of silicomolybdate only the latter one remains. Similar bicarbonate concentration dependence of O2 evolution was obtained in untreated Mn- containing PSII membrane fragments. It is suggested that the K(d) of 20-34 μM is associated with the donor side of PSII while the location of the lower K(d) binding site is not quite clear. The conclusion is made that bicarbonate is an essential constituent of the water-oxidizing complex of PSII, important for its assembly and maintenance in the functionally active state.
URIhttp://hdl.handle.net/10261/121272
DOI10.1073/pnas.94.10.5050
Identifiersdoi: 10.1073/pnas.94.10.5050
issn: 0027-8424
Appears in Collections:(EEAD) Artículos
Files in This Item:
File Description SizeFormat 
accesoRestringido.pdf15,38 kBAdobe PDFThumbnail
View/Open
Show full item record
Review this work
 

Related articles:


WARNING: Items in Digital.CSIC are protected by copyright, with all rights reserved, unless otherwise indicated.